Tuesday, February 19, 2013

CBSE_NCERT 6th Ch-Importance of Air [Solved Questions]


1. Why do mountaineer carry oxygen cylinder while climbing?

Ans: This is because amount of oxygen at high altitude and become difficult to breadth.

2.  Why does smell of perfumes reach us several meters away?
Ans: This is because air is continuously moving it takes the particle of perfumes along with it.

3. Why does crocodile keep it snout out of the water while resting?
Ans: Crocodile keeps it snout out of the water while resting to breathe through nostril.

4. Why do we see bubbles in water before it starts boiling?
Ans: This is because dissolved air is expelled out o heating.

5. Why do animals that live in holes or borrow in soil breadth?
Ans: They breadth in oxygen present between the soil partials.

6. What is the role of air in water cycle?
Ans: Air helps the water vapour to rise up to form cloud.

7. What does air bubbles coming out of soil, when pt in water indicates?
Ans: The presence of air

8. Why long chimneys are installed in factories?
Ans:  To expel harmful smoke and gases away from our noses.

9. You have seen some tiny shining particles moving in the beam of sunlight. What are these particles?
Ans: Dust partials presents in air.

10. Why does the policeman wear a mask?
Ans: vehicles produce smoke, which is bad for health therefore to avoid breathing dust partials by covering face.

11. Why the transparent glass of windows, if not wiped off regularly, appears hazy?
Ans: Air contains some gases, water vapours and dust particles that stick to transparent glass of windows and it appears hazy.

12. Why during an incident of fire, one is advised to wrap a woolen blanket over a burning object.
Ans: Air presents in between the thread of woolen blanket form an insulating medium. It blocks supply of oxygen getting to the fire and the fire goes out.

13. How do plants and animals maintain the balance of oxygen and CO2 in the air?
Ans: Plants take carbon dioxide to prepare food and release oxygen during daytime. This oxygen is taken in by animals and carbon dioxide is released. Thus, plants and animals help in maintaining balance of oxygen 
and carbon dioxide.

14. Why it advised to breathe through nose not through mouth?
Ans: This is because fine hair and mucus present inside the nose prevent dust particles from getting into the respiratory system.

15. Why earthworms come out of the soil, only during heavy rains?
Ans: when it rains heavily, water fills up all the spaces occupied by the air in the soil. Therefore earthworms have to come out for respiration.

16. Why all the oxygen of atmosphere does not get used up though a large number of organisms are consuming?
Ans: This is because the balance of oxygen and carbon dioxide in the atmosphere is maintained by plants and animals.

17. Why does a lump of cotton wool shrink in water?
Ans: A lump of cotton wool shrinks in water because water filled up the empty space that the air has occupied.

18. Why does air quality at every place to place  is not good.
Ans:  It is due to the smoke and gases emitted by the automobiles along with dust particles present in the air.

19. When tightly capped bottle full of water kept in the open sunlight, tiny bubbles were formed all around inside the bottle. Why so happened?
Ans: This is because air dissolved in water starts escaping in the form of tiny bubbles due to heat from the sun.

20. Explain reason why:
(a) A firki does not rotate in a closed area.
(b) The arrow of weather cock points towards a particular direction at a particular moment.
(c) An empty glass in fact is not empty.
Ans: (a) A firki does not rotate in a closed area due to lack of air movement.
(b) The arrow of weather cock points towards a particular direction at a particular moment because of the direction of the movement of wind.
 (c)This is because everything is filled with air.

21 Fill in the blanks    
(a) The ______ makes the windmill rotate.[Wind]
 (b) Air is a ______ of some gases.[mixture]
(c) A weather cock shows the ______ in which the air is moving at that place. [Direction]
(d) Mountaineers carry oxygen ______ with them, while climbing high mountains [cylinder]
(e) The components of air which are harmful to living beings are ____  and  ______. [Dust and smoke]

22. Write true /false
a. Atmosphere has only nitrogen.
b. Gases cannot dissolve in water.
c. Oxygen supports burning.
d. Air acts as a medium for flying.
e. At night plants let out oxygen.
f. Air is transparent.
Ans: (a)  F (b) F (c)  T (d). T (e). F (f)  T

Monday, February 18, 2013

CBSE_NCERT Class 6th Chapter-Waste (Garbage In, Garbage Out )

CBSE 6th Chapter -Waste (Garbage In, Garbage Out )

• Introduction

• Segregation of wastes

• Management of biodegradable wastes

• Composting, Landfills - Structure of a landfill

• Management of Non-Biodegradable Wastes

• Reduce, Reuse, Recycle - Recycling of Plastics, 
Recycling of paper

Garbage Disposal

A large, low-lying area used to dispose garbage is known as a dump. 

A garbage dump is also used as landfill. Garbage collectors collect waste and then dispose it at 
garbage disposals. 

Garbage dumps have flies, cockroaches and mosquitoes, and later turn into breeding grounds for micro-organisms that may cause diseases. That is why these garbage dumps are usually located on the outskirts of a city.

Components of garbage: Garbage has useful and non-useful components.

ü Useful garbage components are those that can be decayed easily. The process of decaying is known as 
composting. Useful garbage components are fruit and vegetable waste, plant and animal waste, tea leaves, coffee grounds and paper. These useful components of garbage are converted into manure in the soil.

ü Non-useful garbage components include polythene bags, plastics, glass and aluminum foils. These take longer to decay. Decaying of these non-useful components is known as decomposition. When non-useful components decay, they release harmful gases that damage the environment. To avoid the adverse impact, these garbage items are sent for recycling. For example, when leaves burn, they release harmful gases and causes air pollution. Moreover, they lead to asthma and lung diseases. That is why leaves should be buried so as to convert them into manure.

ü Vermicomposting
The process of preparing compost with the help of red worms is called vermicomposting. The red worm is a type of earthworm that lives in the soil rich in organic matter, which is a combination of nitrogen-rich and carbon-rich material with plenty of moisture and microbes.
Method of Vermicompositing
A vermicomposting pit is made with a wooden box or big cement rings.  A mesh is spread at the bottom of the pit. Vegetable waste, fruit waste, waste paper which is not shiny or coated with plastic, is spread over the mesh. Water is sprinkled to create moisture so that the red worms can live. A vermicomposting pit takes nearly two to four weeks to completely convert waste into manure.
Waste material that is rich in oils, salt, meat and vinegar stops the growth of red worms. These red worms have a special structure called gizzards with which they grind food material. A red worm eats food equal to its weight every day. Red worms do not survive in too hot or too cold conditions.

Recycling Paper and Plastics

It is important to reuse things than discarding them as waste. Industries use recycled or waste paper to regenerate paper. Paper that is suitable for recycling is called "scrap paper". You can recycle old newspapers, magazines, notebooks and used envelopes, but not waxed paper, oil-soaked paper, paper contaminated with food, carbon paper, thermal fax paper, plastic laminated paper, stickers, and sanitary products or tissues.

Steps involved in recycling paper

ü  Tear paper into small pieces.
ü   Soak these pieces in water for a day.
ü   Make a thick paste and spread it on a net or sieve.
ü   Let water drain off completely
ü  Use an old cloth or newspaper to remove the extra water from the paste and dry it.

ü   Use this paste to get beautiful patterns.

Disadvantages of using of polythene bags

We use many plastic items such as tooth brush, combs, containers, bottles, shoes, toys, wires, frames and bags every day but using plastic is very harmful in terms of health and as well as the environment. Plastics are not suitable for storing cooked food because they emit harmful chemicals when they are exposed to high temperatures. Using plastics causes health problems such as heart disease, diabetes and reproductive dysfunction.

Harmful gases are emitted from burning plastics, which cause cancer and they kill living beings. That is why plastics should be disposed in the right way.
Plastics thrown casually get into drains and sewages, often blocking the way and causing water-logging. So polythene bags should not be used for garbage disposal.

Measures taken to prevent from the dangerous effects of plastics:ü  Reduce, reuse and recycle plastics.
ü  Carry jute or cloth bags for shopping
ü Do not store food items in plastic bags.
ü  Do not burn plastic items.
ü  Recycle plastics so that new plastic items can be made.
ü  Waste that does not decompose should be put in blue dustbins, while waste that decomposes easily should be put in green dustbins.

Vermicomposting
Conversion of the waste generated in the kitchen into organic matter with the combined action of earthworms and micro-organisms is called vermicomposting . The organic matter so formed is used as manure for plants

VI – SCIENCE WORKSHEET: Garbage In, Garbage Out

I. Fill in the blanks :
1. Method of making compost using _____________ is called vermin composting
2. Converting plant and animals wastes into manure is called ____________.
3. ____________ is an area where the garbage is collected.
4. We need to generate ____________ waste.
II. True or False Sentences :
1. Paper can be recycled to get useful products.
2. Drains get choked due to plastic thrown by us.
3. Plastics are eco-friendly.
4. Redworms eat up on green leaves on trees and make compost.
5. Plastics give out harmful gases up on heating or burning.
III. Answer these Questions
1. How do earthworms increase fertility of soil?
2. Rag pickers always suffer from diseases why?
3. Why does composting of leaves better than burning them?
4. Why should plastic food containers be avoided?
5. Why we should not throw away any things that can be recycled?
6. Why recycled plastic are not recommended for storing food in?
8. What is waste management and why it is so important?
9. Which garden worm generally used for Vermi composting.   
10. Why worm box aerated in the process of vermi composting?

Thursday, February 14, 2013

Reproduction in Animals and Endocrine System [8th Science]

(I) answer the following questions in one word

1. What is the age of puberty in girl?

Ans: 10 – 12 years

2. Which gland secretes Corticoid hormones?

Ans: Adrenal Glands

3. What types of fertilization takes place in Man?

Ans: Internal Fertilization

4. What is the other name of Endocrine garland?

Ans; Ductless gland

5. What is the term used for development of Ovum without fertilization?

Ans: Parthenogenesis

6. Name the hormones secreted by pineal glands?

Ans: Melatonin

7. Which gland is called master glands?

Ans: Pituitary Gland

8. When chromosome is not sex chromosomes, what is it called?

Ans: autosomes

9. Name the term used for having X and Y chromosomes.

Ans: Sperm gamete

10. Name the hormones secreted by testes?

Ans: Testosterone

(II) Answer the following questions in brief

1. Why does our body changes when we reach to teens?

Ans: when we reach to teens, Endocrine system of or body regulate the release of hormone that create 
change in our body.

2. How sex determined in some species of Reptiles?

Ans:  In some species of reptile including alligator and turtle, the sex of offspring is determined by the 
temperature at which egg is incubated.

3. What happen to zygote after it is formed?

Ans: A newly formed zygote immediately begins the process of cell division and differentiation and form 
hollow ball made of hundred cells which is called an embryo.

4. How egg -lying animal fertilize their egg?

Ans:  For fertilization, egg -lying animal sits on its eggs to provide sufficient warmth to the egg for development of the embryo inside egg. Fully developed baby bird rapture the egg and young bird emerged out.

5. Differentiate between oviparous and viviparous animals. Give one example of each.

Ans: Differences between oviparous and viviparous animals are:

Oviparous
Viviparous
These animals lay eggs which develop into young ones later on.
These give birth to young ones instead of eggs.
e.g. Birds, frogs, etc.
e.g. Humans, dogs, etc.

6. What is reproduction? Why an individual has some characteristics of father and some of mother?

Ans: Process of producing new individuals is called reproduction. Reproduction is of two types: Sexual reproduction and asexual reproduction
An individual is formed from a zygote which is a result of fusion of sperm from father and ovum from mother. Hence it inherits some characteristics of father and some of mother.

7. What is test-tube baby?

Ans: Oviducts of some women are blocked due to which these women are not be able to bear babies. In these type of cases IVF or in vitro fertilization is done in which freshly released egg and sperms are kept them together for a few hours.
Zygote is allowed to develop for about a week and then it placed in the mother’s uterus and the baby is born and this technique is called as test-tube babies.

8. What is implantation?

Ans: The close attachment of the embryo with the walls of uterus is called implantation.

9. What is placenta?

Ans: A special tissue between the uterus wall and the embryo (foetus) that fulfils the nutritional, respiratory and excretory needs of the foetus from mother's body is called placenta.

10. What is the function of amniotic fluid ?

Ans: The function of amniotic fluid is to protect the foetus against temperature changes and mechanical shocks.

11. What is gestation?

Ans: The development of the foetus inside the uterus till birth is called gestation.

12. What is parturition?

Ans :The birth of a fully developed foetus after the completion of gestation period is called parturition.

13. What is metamorphosis?

Ans: Transformation of a larva into an adult through drastic changes is called metamorphosis.

14. What are the differences between development of young ones in frogs and in humans?

Ans:  
Development in frogs
Development in humans
It takes place outside the body of the female.
It takes place inside the body of the female.
Stages in the development are egg, larva and adult.
Stages in the development are foetus, young one and adult.
The young one is different from the adult.
The young one is similar to the adult.

15. Which hormone is secreted by pituitary gland?

Ans: Growth hormones, Tropic Hormone, Prolactine , Vasopression and oxytocin.

16. What is the function of thyroid glands?

Ans: Thyroid glands produce thyroxin hormones that regulate the metabolism of fats, protein  and carbohydrates.

(III) Answer the following questions in Detail?

1. What are the characteristics of hormones?

Ans: Characteristics of hormones:
(i)They are secreted by glands
(ii) They are poured directly into blood stream.
(iii) They are called chemical messengers
(iv) They regulate body growth and co-ordinate the activities of the body.

2. What is puberty? What happened this stage?

Ans: Puberty is the period during which growing boys or girls undergo the process of sexual maturation. Puberty involves a series of physical stages and the development of the so-called secondary sex characteristics, the physical features associated with adult males and females (such as the growth of pubic hair.

3. What is sexual reproduction? Discuss?

Ans: Reproduction involve two parent organism and produce especial type of cell gamete is called sexual reproduction

Steps that occur during sexual reproduction are:

(a) Formation of Gametes: Males as well as females produce gametes from their reproductive organs. Gametes are the single celled structures that help in reproduction.

(b) Fertilization: The male and the female gametes fuse together to form zygote.

(c) Development of Zygote: The zygote divides and develops to give rise to the new individual.

4. What is gland? What is the ‘endocrine system’?

Ans: A group of cells produce and secretes chemicals (hormones) are called glands.

Endocrine system is an integrated system of organ which regulates the release of hormones.  A hormone is a chemical substance produced by specially formed tissue called Endocrine glands or ductless glands. This system help in regulating metabolism, tissue function, growth and development of body.

5. Why pituitary glands are known as master glands?

Ans: It is a tiny gland of the size of a pea attached to the hypothalamus of the brain. Pituitary glands are known as master glands because it produces hormones that control several other endocrine glands.

7. Why frogs and fish produce a large number of gametes?

Ans: In frogs and fish, external fertilization takes place with the help of water. Their gametes are released in the water where other animals can feed on them. Hence, to ensure fertilization of at least few of the gametes, these animals produce a large number of gametes.

(IV) Multiple Choice Questions

1. A placental mammal would be
(a) larviparous.  (b)   viviparous.  (c) external fertilizers. (d) oviparous.      Answer: (b)  

2. The male reproductive system includes all EXCEPT which of the following?
(a) testes (b) epididymis (c) penis  (d) fimbriae                                       answer:(d)  

3. In the human male, the tube used to carry both sperm and urine is the
(a) ureter. (b) seminiferous tubule.  (c) vas deferens. (d) urethra.       answer:(d)]

4. In the human male, sperm cells are produced in the
(a) interstitial tissue. (b) urethra.  (c) seminiferous tubules. (d) vas deferens.    answer: (C)

5. Secondary sexual characteristics in the male are directly maintained by the hormone
(a) testosterone.  (b) estrogen.       (c) FSH.         (d) TSH.                     answer: (a)

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For further study:

CBSE Class VIII Science
Physics             Chemistry            Biology          8th Sample paper            8th Social Science

Class VIII Mathematics 
 VIII Algebra                       VIII Commercial Maths            VIII Geometry & Mensuration

Friday, February 1, 2013

Solve Sample paper [Biology] Summative Assessment – II


1. Which animal tissue is commonly known as packaging tissue? [1]

Ans: Areolar Tissue

2. What do you mean by photoperiod? Name two processes that are dependent on photoperiod.[2]

Ans: Photoperiod is related to exposure of plants to the duration of sunlight.

Germination, growth and flowering (any two) in case of plants are dependent on Photoperiod.

3. What will happen if: 
i) the skin epithelium is not stratified. 
ii) Stratified squamous epithelium lines blood vessels. [2]

Ans: i) There will be no protection to the inner layers and wear and tear will be more.

       ii) The exchange of substances through selectively permeable surface cannot take place.

4. Name the target organ/organ system of AIDS virus. What is the cause of death in case of people suffering from AIDS? [2]

Ans: Lymph nodes/Immune System.
In absence of a strong Immune system ,minor infections can turn in to serious problems.

5.To increase productivity per unit area ,the farmers grow two different types of crops on the same field in definite rows. What is this practice called? What care is required to be taken before selecting two crops for such practice and why? Give any two reasons [3.]

Ans: Intercropping
The nutrient requirements of two crops are different
i) Maximum utilization of the nutrients.
ii) Prevents spread of pests and diseases to all plants belonging to one crop in a field.

6. Draw a neat diagram of the leaf epidermis showing pores through which exchange of gases takes place. Label any two parts giving one function of each.[3]

Ans: Guard cell- closing and opening of stomata
Stomata- exchanging gases with atmosphere
Epidermis-Protection to all parts of plant

7.i) Which of the following diseases are protozoan in origin?
   a) Dengue b)Malaria c)Kalaazar d)AIDS
  ii) Suggest any two ways you would like to adopt, to prevent being infected by them

Ans: i) Malaria and Kalaazar
 ii)
(a)We should not throw waste or garbage in open in the street (b) There should not be open drain with stagnant water

8. i)Write any three differences between Procaryotic and Eucaryotic cell.
   ii) Draw a neat diagram of a typical prokaryotic cell and label any two parts.[5]

Ans: i) Procaryotic cell                                 Eucaryotic cell
(a) Nuclear region poorly defined                 ( a)Nuclear region well defined and  surrounded by a due to lack of nuclear membrane                            nuclear membrane.
(b) Single chromosome                                   (b)More than one chromosome
(c) Membrane bound cell organelles               (c)membrane bound cell organelles absent. Present

9. (a) Define the following terms:[5]
             (i) Lichens (ii) Cryptogamae (iii) Phanerogams
    (b) Why whales are not grouped in the fishes?
    (c) What is bilateral symmetry?

Ans: (a)
(i) Lichens: Some fungal species live in permanent mutually dependent relationships with blue-green algae. Such relationships are called symbiotic and the symbiotic life forms are called lichens.

(ii) Cryptogamae: The reproductive organs of the thallophytes, the bryophytes and the pteridophytes are very inconspicuous and are therefore, called 'cryptogamae'. It means the plants with 'hidden reproductive organs'.
(iii) Phanerogams: The plants with well differentiated reproductive tissues that ultimately make seeds are called 'phanerogams'.

(b) Whales can swim in water like the fishes but are not fish as they respire with lungs and have four chambered heart and mammary glands, so they are mammals.

(c) When the body of an organism can be cut into two similar halves which are mirror image of each other, only by one plane then the organism is said to have bilateral symmetry

10. (a) Give reasons for the following:[5]
(i) Bryophytes are called amphibians of plant kingdom.
(ii) From Phylum Platyhelminthes onwards, animals are categorized as 'triploblastic'.
(iii) The presence of 'coelom' in an animal's body is considered as advantageous.
(b) What are oviparous animals?
(c) Name the phylum in which pharyngeal gill slits are present.

Ans: (a) (i) Just like amphibians, bryophytes require water for fertilization as their gametes require aqueous medium for movement.

(ii) There are three layers of cells from which differentiated tissues can be made. This allows inside and outside body linings as well as some organs to be made. There is thus some degree of tissue formation.

(iii) Coelom is a true internal body cavity in which well-developed organs can be accommodated.

(b) The animals which lay eggs are known as oviparous animals.

(c) Chordata.

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